The present invention pertains to an electrical circuit and method for wiping from one television video source to another video source.
In television broadcasting, several special effects systems are employed on a regular basis. One of these is employed for the wiping from one source of video to another either by a horizontal wiping action from left to right of the reproduced television raster, a vertical wipe from top to bottom, or a diagonal wipe which is a combination of horizontal and vertical waveforms. The horizontal wipe is used to explain the invention. With color television broadcasting, when switching from one video source to another during wiping, frequently the phase of the color burst signal present during the horizontal blanking interval is different from one source to another. If the difference is greater than 5.degree. maximum, a significant tint variation between the two video sources during a wipe is noticeable. Although this problem has been recognized in the prior art, as for example, illustrated by U.S. Pat. Nos. 2,964,589 and 4,180,829; the prior art does not suggest a system as provided herein for mixing the color burst information during the blanking interval of each scan interval while wiping from one video source to another during the video signal information portion of each scan interval.